Thus, IL-17 and IFNγ double-positive CD4+ T cells constituted a median of 46.8% (IQR 26.3–59.1) of IL-17–producing cells in the joint (n = 14), as compared with a median of 12.0% (IQR 4.4–15.5) in control PBMCs (n = 9) and 16.1% (IQR 8.7–23.9) in JIA PBMCs (n = 14), both of which were significantly different from the median in SFMCs (P < 0.001 for each comparison). This evidence concerns the gene IL17A and juvenile idiopathic arthritis.